Search

As mudanças climáticas no século XXI é uma realidade inconteste. Diversos efeitos e impactos vêm sendo registrados sobre o clima e, como consequência, sobre a sociedade em várias regiões do planeta. Eventos extremos cada vez mais severos estão sendo observados, destacando-se secas extremas e chuvas intensas, poucas vezes registradas no passado. O que possibilitou estudos envolvendo mudanças no clima foi à alta performance dos modelos climáticos disponíveis, que simulam as propriedades dinâmicas da atmosfera com uma precisão aceitável. Tal processo acarreta a presença de erros sistemáticos nas saídas dos modelos climáticos, devido a imperfeição ao discretizar os processos que ocorrem na atmosfera. Mediante estas questões, o objetivo deste trabalho consiste em aplicar a técnica de correção de erros sistemáticos percentil por percentil, realizada para a precipitação total e a temperatura média da estação meteorológica da Bacia Hidrográfica do Ribeirão Jaguara (BHRJ), localizada em Minas Gerais e, posteriormente, verificar a tendência da precipitação total e temperatura média ao longo do século utilizando diferentes cenários. Para tal análise, utilizou-se as projeções oriundas dos modelos climáticos Eta-HadGEM2-ES, Eta-MIR­­­­OC5 e Eta-CanESM2, sob os cenários RCP4.5 e RCP8.5. Os resultados mensais das variáveis, projetados pelos três modelos, sugerem que foi possível capturar os padrões de variações mensal até o final do século XXI (2006-2099), com cenários RCP4.5 e RCP8.5, quando comparados aos resultados do clima presente (1961-2005).

Sao Tome and Principe is a small insular African country extremely vulnerable to rising sea levels and impacts such as inundation, shore line change, and salt water intrusion into underground aquifers. Projections of climate change have considered coarse model resolutions. The objective of this work is to dynamically downscale the global model projections to 4-km resolution and to assess the climate change in the Sao Tome and Principe islands. The global climate projections are provided by the Canadian Earth System Model under two Representative Concentration Pathways greenhouse gas scenarios, RCP4.5 and RCP8.5. The downscaling is produced by the Eta regional climate model. The baseline period is taken between 1971 and 2000, and the future climate period is taken between 2041 and 2070. The 2-m temperature simulations show good agreement with station data. The model simulates temperature more accurately than precipitation. The precipitation simulations systematically show underestimation and delay of the rainy and the dry seasons by about 1 month, a feature inherited from the global climate model. In the middle of the 21st century, projections show the strongest warming in the elevated parts of the Sao Tome Island, especially in February under RCP8.5. Warmer nights and warmer days become more frequent in the islands when compared with those in the present. While under RCP4.5, precipitation increases in the islands; under RCP8.5, it decreases everywhere in both islands. Heavy precipitation rates should increase, especially in the south-southwestern parts of the Sao Tome islands. Detailed spatial variability of the temperature and precipitation changes in the islands can only be revealed at very high spatial model resolution. Implications for the potential energy production from two major river basins are assessed in this work.

Changes in precipitation and air temperature may produce different impacts on the hydrological regime, compromising water supply. This study focuses on climate change impacts in the Verde River Basin (VRB), a tropical headwater basin in southeast Brazil, located in the state of Minas Gerais. The Variable Infiltration Capacity model (VIC) was calibrated and validated in the Verde River Basin. The downscaling (Eta Regional Climate Model, at 20-km resolution) of three Global Circulation Models (CanESM2, HadGEM2-ES and MIROC5) were used to drive the VIC for a historical baseline (1961-2005) and three time-slices (2011-2040, 2041-2070 and 2071-2099), under RCPs 4.5 and 8.5 scenarios. The scenarios were used as input in the hydrological model after bias correction. The hydrological model (VIC) showed satisfactory statistical performance in calibration and validation, with CNS varying from 0.77 to 0.85 for daily and monthly discharges; however, it overestimated some peak flows and underestimated the recession flows. Multi-model ensemble means predict increases of the minimum and maximum monthly average temperature for the investigated area at the end of the century. The Eta-CanESM2 indicated greater warming, mainly for RCP8.5 at the end the century, whereas Eta-HadGEM2-ES showed higher reduction in the precipitation for RCP4.5 at the beginning of the century and for RCP8.5 at the end the century, negatively impacting the evapotranspiration and discharge. Among the Regional Climate Models (RCMs), the Eta-MIROC5 showed minor changes in the components of the hydrological cycle. This study suggests that Global Circulation Models represent an additional uncertainty, which should be accounted for in the climate change impact assessment. Resumo Mudanças na precipitação e na temperatura do ar podem produzir diferentes impactos no regime hidrológico, causando colapso no abastecimento de água. Este estudo focaliza nos impactos das mudanças climáticas na bacia do Rio Verde (VRB), uma bacia hidrográfica de cabeceira no sudeste do Brasil, localizada em Minas Gerais. O modelo hidrológico Variable Infiltration Capacity (VIC) foi calibrado e validado na bacia do Rio Verde. O downscaling (Modelo de Clima Regional Eta, com resolução de 20 km) de três Modelos de Circulação Global (CanESM2, HadGEM2-ES e MIROC5) foram usados no VIC com dados históricos (1961-2005) e em três intervalos de tempo (2011- 2040, 2041-2070 e 2071-2099), nos cenários RCPs 4.5 e 8.5. Os cenários foram usados como entrada no modelo hidrológico após a correção do viés. O modelo hidrológico (VIC) apresentou desempenho estatístico satisfatório na calibração e validação, com CNS variando de 0,77 a 0,85 para as vazões diárias e mensais; no entanto, superestimou alguns fluxos de pico e subestimou os de recessão. A média do conjunto de modelos prevê aumentos da temperatura média mensal mínima e máxima no final do século. O Eta-CanESM2 indicou maiores temperaturas, principalmente para RCP8.5 no final do século, enquanto Eta-HadGEM2-ES apresentou a maior redução na precipitação para RCP4.5 no início do século e para RCP8.5 no final do século, impactando negativamente na evapotranspiração e vazão. Entre os Modelos Climáticos Regionais (MCRs), o Eta-MIROC5 apresentou pequenas alterações nos componentes do ciclo hidrológico. Este estudo sugere que Modelos de Circulação Global representam incertezas adicionais, que devem ser consideradas na avaliação do impacto das mudanças climáticas.

Resumo As mudanças climáticas no século XXI é uma realidade inconteste. Diversos efeitos e impactos vêm sendo registrados em várias regiões do planeta. Este trabalho tem por objetivo avaliar a associação do modelo hidrológico MHD-INPE ao modelo atmosférico Eta/CPTEC, a fim de simular o impacto de mudanças climáticas na Bacia Hidrográfica do Ribeirão Jaguara, localizada no sul do estado de Minas Gerais. Para tal fim, foram utilizados dois cenários (RCP4.5 e RCP8.5) de três modelos globais (HadGEM2-ES, MIROC5 e CanESM2), regionalizados pelo modelo Eta. Os resultados da calibração e validação mostraram uma boa performance MHD-INPE em simular a vazão da BHRJ. Após a correção de viés, as saídas dos cenários foram usadas como entrada no MHD-INPE. As projeções climáticas corrigidas dos cenários resultaram em predominante redução da precipitação ao longo do século. Os resultados das projeções da temperatura mostraram aumento consensual por parte dos modelos climáticos, em ambos os cenários. As estatísticas da curva de permanência das vazões advindas das simulações climáticas mostraram um bom desempenho do MHD-INPE na simulação do clima presente. Abstract Climate change in the 21st century is an undisputed reality. Several effects and impacts have been registered in society in several regions of the planet. This work objective is to evaluate an association of the hydrological model MHD-INPE with the atmospheric model Eta/CPTEC to simulate the impact of climate change in the Jaguara Creek Basin, located in the south of the state of Minas Gerais. For this purpose, two scenarios (RCP4.5 and RCP8.5) of three global climatic models downscaled by the Eta model (HadGEM2-ES, MIROC5 and CanESM2) were used. The results of the calibration and validation shows a good performance of the MHD-INPE model in simulating the JCR daily discharge. The results of the scenarios were used as input to the MHD-INPE model after bias correction. Regarding the corrected climate projections, they resulted in a predominant reduction of the rainfall throughout the 21st century. The results of the projections of temperature showed an increase through the climatic models in both scenarios. The statistical of the flow duration curve (FDC) resulting from the simulations of the Eta model showed a good performance of the MHD-INPE in the simulation of the baseline period.

This paper assessed the potential impacts of climate change on maize productivity in the Brazilian Northeast. To achieve this objective, bias-corrected regional downscaled scenarios from three global models for the representative emission pathways, RCP4.5 and RCP8.5, for the periods 1980–2005, 2007–2040, 2041–2070, and 2071–2099 were used as input data for a crop productivity model. Because increased temperatures are likely to shorten the crop cycle length, thus reducing productivity, we investigated the lengthening of the growing cycle as an adaptation strategy. To cope with the reduction of rainfall projected by future climate scenarios, we analyzed the potential impact of irrigation on productivity. The results showed that climate change effects would be mostly negative for maize rainfed agriculture, particularly for the worst-case scenario (RCP8.5, 2071–2099), in which losses were expected to reach more than 60%. However, productivity losses were limited to a maximum of 30% for all RCP4.5 scenarios and before 2070 for the RCP8.5 scenario. The use of maize cultivars with a longer crop cycle for rainfed agriculture was likely to increase the average productivity in all scenarios, although it came at the expense of increasing the risk of crop failure. Regarding the use of irrigation, there was an improvement in productivity for both the short- and long-cycle cultivars, although longer crop cycle cultivars had a decisive advantage, with a drop in yield of less than 20% for all RCP4.5 scenarios and for the RCP8.5 scenario until 2070 compared to the present climate. We estimated the total production and the increase in water demand based on the existing and projected irrigated areas in the region and concluded that it is possible to avoid significant losses in total maize production in the region for all scenarios, with the exception of the 2071–2099 RCP8.5 scenario. However, sustaining such levels of production requires a significant increase in water consumption (up to 140%).

Sao Tome and Principe is a small insular country in the west coast of Central Africa. The small dimensions of the islands and the limited natural resources put these islands under highly vulnerable to climate change. To assess the possible future impacts and risks on their agricultural activities, the high-resolution 4-km downscaled climate change projections using Eta regional climate model are used. A crop risk index (CRI) is proposed to assess the risk of climate change on cocoa (Theobroma cacaoL.), pepper (Piper nigrumL. andPiper guinesseL.), taro (Colocasia esculenta(L.) Schott), and maize (Zea maysL.). The index takes into account the vulnerability to climate conditions and the crop yield in the future, and it is classified intovery-high,high,moderate,low, andvery-low. The climate change projections indicate increase in the risk of taro crop, partly due to thermal stress and partly due to the susceptibility to the leaf blight crop disease in taro. The risk of production of the pepper crop is very-high, mainly due to water stress. In mountain regions, the greater risk is due to the thermal stress caused by low temperatures. The cocoa crop is at risk due to water stress, mainly in the northwestern part of the Sao Tome Island, where major local production occurs. The projection indicates increase of the area with very-high risk to maize crops due to the increase of thermal stress and susceptibility to rust. In addition, in parts of the coastal regions, the risk changed from very-low to high risk, due to the low productivity potential. In general, the risks of the four major crops of Sao Tome and Principe increase in the future climate conditions.

In this paper, we evaluated the performance of the model AquaCrop for crop yield forecasting in the Brazilian semiarid (BSA) using meteorological observation and Eta model seasonal climate forecasts as input data. The study area is characterized by low rainfall that is poorly distributed throughout the rainy season; thus, the region's agricultural productivity is vulnerable to climate conditions. AquaCrop was first calibrated using field experiments and subsequently applied to simulate an operational crop yield forecast system for maize under rainfed conditions. Simulations were performed with daily data for 37 growing seasons for the period 2001–2010. The seasonal climate forecast was used in combination with observed meteorological data to anticipate the crop forecast. Soil characteristics were derived from pedotransfer functions (PTFs). We were able to demonstrate the ability of the seasonal crop yield forecast system to provide timely and accurate information about maize yield at least 30 days in advance of the harvest. The development of improved crop yield forecasting system is crucial for implementing drought-preparedness measures in the BSA region.

Landform classification is important for representing soil physical properties varying continuously across the landscape and for understanding many hydrological processes in watersheds. Considering it, this study aims to use a geomorphology map (Geomorphons) as an input to a physically based hydrological model (Distributed Hydrology Soil Vegetation Model (DHSVM)) in a mountainous headwater watershed. A sensitivity analysis of five soil parameters was evaluated for streamflow simulation in each Geomorphons feature. As infiltration and saturation excess overland flow are important mechanisms for streamflow generation in complex terrain watersheds, the model’s input soil parameters were most sensitive in the “slope”, “hollow”, and “valley” features. Thus, the simulated streamflow was compared with observed data for calibration and validation. The model performance was satisfactory and equivalent to previous simulations in the same watershed using pedological survey and moisture zone maps. Therefore, the results from this study indicate that a geomorphologically based map is applicable and representative for spatially distributing hydrological parameters in the DHSVM.

Agricultural production risk is getting increasing attention in the science and the policy domain due to its strong connection with food security and its potential to trigger systemic risks. Particularly in semi-arid regions, weather and environmental conditions can seriously affect agricultural production. Brazil stands out exceptionally as it has one of the most populated semi-arid areas globally. Nevertheless, risk assessment of crop production for these regions is lacking, but essentially needed for policy and risk management purposes. To fill part of this gap, this paper provides first estimates of crop yield risk for the semi-arid in Brazil on the municipality level from an empirical perspective. It was found that many highly vulnerable municipalities are located in states such as Ceara, Piaui, Pernambuco, and Paraiba. These hotspot regions may be prioritized in terms of public investments in order to help them decrease current and future vulnerability related to crop production. Especially climate change impacts may worsen the situation considerably in the future and should be included already in current adaptation strategies.

Conduziu-se este trabalho, com o objetivo de fornecer informações a respeito da investigação experimental realizada na estação piloto no Núcleo de Estudos em Cafeicultura (NECAF/UFLA), para tratamento de água residuária do café (ARC) especificamente, o monitoramento de um Reator Anaeróbio Híbrido (RAH), utilizando minifiltros preenchidos com dois tipos de meio suporte (argila expandida e seixo rolado). O RAH possuía fundo falso e foi utilizado como inóculo lodo anaeróbio de Upflow anaerobic sludge blanket reator (reator anaeróbio de manta de lodo) - UASB (escala-plena), de esgoto doméstico. O sistema foi monitorado por meio de parâmetros operacionais e de análises químicas e físico-químicas. Foi constatado que a fase experimental em que se deu o experimento dificultou a eficiência do RAH por ter sido submetido a cargas inferiores às previstas, uma vez que o efluente passava por tratamento em outras unidades, minimizando assim, a concentração orgânica a ser tratada. O RAH apresentou concentrações afluentes médias de: 484; 168 e 92 mg DQOtot L-1 e concentrações efluentes médias de 344; 159 e 90 mg DQOtot L-1, para os tempos de detenção hidráulica (TDH) de 28,5; 23,7 e 18,0 horas, respectivamente. O RAH apresentou equilíbrio com relação aos parâmetros medidos e boa estabilidade. O efluente analisado não apresentou riscos de salinidade, uma vez que a CE ficou na faixa, entre 0,70 e 3,0 dS m-1 e os SDT, entre 450 a 2000 mg L-1. Quanto à sodificação, a Razão de Adsorção de Sódio (RAS) ficou entre 0 e 3 e a CE>0,7 dS m-1, podendo ser reutilizado para irrigação da maioria das culturas e solos. The purpose of this work is to supply information regarding to the experimental investigation carried out in a pilot scale system, located at Coffee Study Research Center (NECAF/UFLA). The research focused mainly on a Hybrid Anaerobic Reactor (HAR) operating with mini-filters filled with two types of physical support (expanded clay and pebble "round quartz stone"). The HAR used a three-phase-separator; and during the start-up, sludge from a full-scale UASB reactor treating domestic wastewater was utilized. The experimental results did not show great efficiency due to the removal of the organic matter in other treatment units located before the HAR, minimizing in this way the concentration of organic matter to be treated in the HAR. The HAR presented an average affluent concentration of: 484, 168, and 92 mg CODtot L-1, and an average effluent concentration of: 344, 159, and 90 mg CODtot L-1. The HAR also presented good balance in relation to the parameters measured, as well as good stability.